1. Technical Field
The disclosed technology relates to terminating a harmonic component of a signal.
2. Description of the Related Technology
In relatively high frequency applications, such as radio frequency (RF) applications, unwanted signal reflection and/or noise can occur. Such unwanted signal reflection and/or noise can occur at a fundamental frequency of the signal and/or other frequencies, such as harmonics of the fundamental frequency of the signal. To reduce the impact of signal reflection and/or noise, impedance matching can be implemented. One illustrative application in which it is advantageous to minimize unwanted signal reflection and/or noise is a power amplifier system.
Power added efficiency (PAE) is one metric for rating power amplifiers. In addition, linearity is another metric for rating power amplifiers. PAE and/or linearity can be metrics by which customers, such as original equipment manufacturers (OEMs), determine which power amplifiers to purchase. For instance, power amplifiers with a PAE below a certain level may not be purchased by a customer due to the impact of PAE on the customer's product. A lower PAE can, for example, reduce the battery life of an electronic device, such as a mobile phone. However, enhancing PAE can come at the cost of adversely impacting linearity. Similarly, improving linearity can cause a decrease in PAE. At the same time, customers want power amplifiers with high linearity and high PAE.
A load line at an output of a power amplifier can impact both PAE and linearity. Some conventional power amplifier systems have included a load line to match an impedance of the power amplifier output at a fundamental frequency of the power amplifier output signal and also to perform harmonic termination. However, it has proved difficult to match an impedance of the fundamental frequency of the power amplifier output while including harmonic termination in a way that optimizes both PAE and linearity. Accordingly, a need exists to improve both linearity and PAE of a power amplifier.